giant ironweed

Giant ironweed (Vernonia gigantea) is a hardy, drought-tolerant plant that prefers moist soil conditions and moderate to regular watering. During the growing season, water deeply and slowly (so the water can penetrate several inches) once per week, or more often if necessary during dry periods. Allow the soil to dry out slightly between waterings. During the winter months, reduce the frequency to once a month or less.

Giant ironweed requires at least 6 hours of direct sunlight a day to thrive. This is optimal during the summer when the sun is high in the sky, providing more intense amounts of radiation and heat. During the winter, when the sun is lower in the sky, the plant will need more sunlight exposure in order to make up for the decrease in intensity. The plant may even need up to 8-10 hours of direct sunlight a day depending on its location and the severity of the winter season.

Pruning giant ironweed (Vernonia gigantea) should be done in March or April, once the plant has finished flowering. Pruning this plant should be limited to removing dead flower stalks and thinning out excess plant material to maintain its size and shape. It is important to not take off too much of the foliage as this can reduce the structural stability of the plant. Pruning should be limited to removing no more than 1-third of the foliage and stems. Additionally, any weak, damaged, or diseased stems should also be removed from the plant.